One can tell when a good writer is ‘breaking the rules’ for perfectly good reasons. To me, breaking the conventions, challenging grammatical rules now and again is as important as knowing them. Ignorance of the rules will immediately mark you as a dilettante or charlatan. Just the same, hidebound adherence to them can suck all the spirit out of a piece of work.
Van Gogh learned to paint by copying the masters, and then broke the rules and remade art with his own. In similar fashion, I think, a writer learns from years of reading and initial imitation, until finally he or she knows the thrill of powerful authenticity, of finding one’s own voice. That’s one reason why the rules have to be challenged, bent and marvelously refashioned. One is still working with grammar, punctuation, syntax, metaphor, just as a painter works with brushes, pigments, canvas, paper, and oils. But it would be a poor painter who cannot remake boundaries, and a poor writer who dares not push the medium.
The art of writing benefits from those with the courage to step into new territory. One need not be timid, if one has filled the years with this beautiful work, because one walks, or leaps, perfectly equipped, into the unknown. But blunder into new territory with no mastery and you are a zombie trying to tango. It’s funny how that works.